The present invention relates generally to a safety structure for detecting and enclosing fluid leakage around a valve. More particularly, the present invention is concerned with safety structure for detecting and preventing fluid leakage around an exposed rotatable stem of a valve having a element connected to the stem which is rotated between an open and a closed position to control fluid flow through the valve.
Valves are commonly used to control fluid flow through pipelines and other fluid circulating systems. One such valve in common use is a valve having a rotatable valve element disposed within the valve which is rotated a quarter of an turn between an open and a closed position for controlling fluid flow through the valve. A rotatable non-rising valve stem extends from the exterior of the valve into the valve body to connect with the valve element for rotating the valve element between its open and its closed position. A single seal structure between the valve body and the externally projecting valve stem circumscribes the valve stem and prevents leakage from the interior of the valve past the valve stem. However, such single seal valves are eventually subject to leakage around their seal structure due to wear or failure of the seal structure between the body of the valve and the valve stem. With the increasing emphasis on environmental quality, leakage of gas, oil, or other toxic or hazardous fluid to the environment surrounding the valve is unacceptable. Consequently, a need exists for a retrofittable structure which may be added to the valve to contain or sense leakage around its single seal structure and prevent leakage of gas, oil, or other toxic or hazardous fluid to the environment surrounding the valve.
A large number of such single seal valves are already in use, and the manufacture of this type of valve continues. Consequently, there is a great need for a retrofit structure for this type of valve to enclose the external portion of the valve stem for detecting and preventing leakage of gas, oil, or other toxic or hazardous fluid around the seal structure of the valve so as to avoid such toxic or hazardous fluid escaping to the environment.